The present invention relates to a weigher apparatus for measuring can type works or the like in standing posture on a product line and, more particularly, to a weigher apparatus for weighing cans, conveyed by a conveyor, by transferring them onto a weighing conveyor. 2. Description of the Related Art
As shown in FIG. 19, when works such as aerosol cans are to be weighed while they are conveyed on a product line, a conventional weigher apparatus 4 has been used. In this weigher apparatus 4, a work conveyed by a conveyor 1 is transferred onto a weighing conveyor 2 arranged along a conveyor path continuous with the conveyor 1, and the weight of the work is measured on the basis of a signal from a weigher 3 while the work is conveyed on the weighing conveyor 2.
In a weigher apparatus of this type, in which the weighing conveyor 2 is directly connected to the conveyor 1, if works conveyed by the conveyor 1 are not spaced at predetermined intervals or more, two or more works are simultaneously placed on the weighing conveyor 2, and hence weighing by the weighing conveyor 2 cannot be properly performed.
For this reason, a weigher apparatus of another type has also been realized. In this weigher apparatus, conveyed works are transferred onto a weighing conveyor at regular intervals, and weighed works are unloaded at regular intervals.
FIG. 20 is a plan view showing a schematic arrangement of a conventional weigher apparatus of this type. In a weigher apparatus 10, a load conveyor 11, a weighing conveyor 12, and an unload conveyor 13 are arranged in a line. Works which are conveyed by the load conveyor 11 at irregular intervals are engaged with notched portions 15 formed in the outer peripheral portion of a first rotating carrier 14 at equal intervals so as to be rotated/moved to the load side of the weighing conveyor 12.
A work W which is moved to the load position of the weighing conveyor 12 is conveyed on the weighing conveyor 12 while it is guided by a linear guide plate 12a. The work which is weighed during this convey is rotated/moved onto the unload conveyor 13 while it is engaged with a notched portion 17 of a second rotating carrier 16.
The first and second rotating carriers 14 and 16 are so-called star-wheels, whose rotational speeds are set to be equal. The rotational phase of the notched portions of the first rotating carrier 1 is shifted from that of the second rotating carrier 16 by a period of time required to convey a work on the weighing conveyor 12.
With this arrangement, the intervals at which works are loaded on the weighing conveyor 12 are predetermined intervals determined by the rotational speed of the first rotating carrier 14, and works are unloaded from the weigher apparatus 10 at predetermined intervals.
As in this weigher apparatus 10, however, if the convey direction of the weighing conveyor 12 is substantially perpendicular to the direction in which a work is loaded on the weighing conveyor 12 by the first rotating carrier 14, the loaded work may be caught by the conveyor belt of the weighing conveyor 12 to fall or sway.
Especially in a case where works filled with liquids, such as can type works, are to be weighed, the contents of the works are swayed due to this rapid change in convey direction, resulting in a considerable deterioration in weighing precision.
In addition, this phenomenon becomes more conspicuous with an increase in rotational speed of the first rotating carrier 14 and in convey speed of the weighing conveyor 12, interfering with an increase in overall weighing speed.
In order to solve this problem, the weighing conveyor 12 may be arranged along the common tangent line of the first and second rotating carriers 14 and 16. In this case, however, the convey length of the weighing conveyor 12 must be increased by an amount corresponding to a convey length within which a work transferred onto the weighing conveyor 12 is in contact with the notched portion 15 and cannot be weighed. This makes it impossible to increase the weighing speed.